On 08/11/2015 08:39 AM, Wolfram Sang wrote:
> On Thu, Jun 18, 2015 at 12:57:38PM -0700, York Sun wrote:
>> Based on i2c-mux-gpio driver, similarly the register-based mux
>> switch from one bus to another by setting a single register.
>> The register can be on PCIe bus, local bus, or any memory-mapped
>> address. The endianness of such register can be specified in device
>> tree if used, or in platform data.
>>
>> Signed-off-by: York Sun <yorksun@xxxxxxxxxxxxx>
>
> Thanks for this driver!
>
> ...
>
>> +- no-read: The existence indicates reading the register is not allowed.
>
> Given that we have "read-only" properties already, I'd prefer this one
> to be "write-only".
Sure. That's easy to fix.
>
>> +For each i2c child node, an I2C child bus will be created. They will
>> +be numbered based on their order in the device tree.
>
> This is a Linux specific detail (which can be overridden by aliases), so
> it should not be in this document, I'd say.
OK. I can remove it.
>
>> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
>> index f6d313e..77c1257 100644
>> --- a/drivers/i2c/muxes/Kconfig
>> +++ b/drivers/i2c/muxes/Kconfig
>> @@ -29,6 +29,17 @@ config I2C_MUX_GPIO
>> This driver can also be built as a module. If so, the module
>> will be called i2c-mux-gpio.
>>
>> +config I2C_MUX_REG
>> + tristate "Register-based I2C multiplexer"
>> + help
>> + If you say yes to this option, support will be included for a
>> + register based I2C multiplexer. This driver provides access to
>> + I2C busses connected through a MUX, which is controlled
>> + by a sinple register.
>
> Typo here. And keep the sorting, please.
Will fix.
>
>> obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
>> +obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
>
> Keep the sorting, please.
>
>> obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
>> obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
>> obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
>
>> + adapter = of_find_i2c_adapter_by_node(adapter_np);
>> + if (!adapter) {
>> + dev_err(&pdev->dev, "Cannot find parent bus\n");
>
> I don't think we should print something when deferring.
OK.
>
>> + return -EPROBE_DEFER;
>> + }
>> + mux->parent = adapter;
>> + mux->data.parent = i2c_adapter_id(adapter);
>> + put_device(&adapter->dev);
>> +
>> + mux->data.n_values = of_get_child_count(np);
>> + if (of_find_property(np, "little-endian", NULL)) {
>
> You should check for a "big-endian" property as well, no?
I use the little-endian as an option to indicate the nature of litten-endian
register. It is default to big-endian if this property doesn't exist. I prefer
this way unless you strongly suggest to add both and throw out an error if
neither exists.
>
>> + parent = i2c_get_adapter(mux->data.parent);
>> + if (!parent) {
>> + dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
>> + mux->data.parent);
>> + return -EPROBE_DEFER;
>
> Ditto about printing when deferred probing.
OK.
>
>> +static int i2c_mux_reg_remove(struct platform_device *pdev)
>> +{
>> + struct regmux *mux = platform_get_drvdata(pdev);
>> + int i;
>> +
>> + for (i = 0; i < mux->data.n_values; i++)
>> + i2c_del_mux_adapter(mux->adap[i]);
>> +
>> + i2c_put_adapter(mux->parent);
>> +
>> + dev_dbg(&pdev->dev, "Removed\n");
>
> No need for that debug. The driver core has debug output for that.
Will remove.
Thanks for reviewing. I will send a new version after testing.
York
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